1. Field of the Invention
The present invention relates to a washing machine and more particularly, to a system for aligning a wash basket concentrically about the rotational axis of the basket in a manner that decreases runout.
2. Description of Related Art
Typically, a conventional vertical axis automatic washer has a tub and a wash basket vertically aligned within the tub. A drive block supports the wash basket and a spin drive tube extends longitudinally through apertures positioned centrally within the wash basket and drive block. The spin drive tube is driven by a motor that operates the spinning action of the wash basket. It is desired to have the wash basket concentric about a central axis extending the length of the spin drive tube to reduce wash basket runout during the spin cycle.
Conventional automatic washers have at least a wash and spin cycle. During the spin cycle, the spin drive tube drives the wash basket in a spinning motion to force wash liquid out of the wash basket and clothes. The wash basket may be spinning at a rate of 600 to 1000 rpm so it is important that the wash basket is aligned with the central axis or it will become out of balance and wobble or vibrate. When the wash basket becomes out of balance, it may hit the side of the wash tub causing noises. In extreme out of balance situations, the movement of the wash basket hitting the wash tub may cause the washer to xe2x80x9cwalkxe2x80x9d. Additionally, since there is a current trend for higher wash basket capacity without an increase in the size of the cabinet frame, it is necessary to have lower tolerances to maintain control over the basket clearance.
In an automatic washer having a drive block supporting the wash basket, a portion of the drive block is inserted through a central aperture in the bottom of the wash basket and the wash basket bottom surface rests on another portion of the drive block. The spin drive tube extends through a central aperture in the drive block and in the wash basket bottom. The wash basket is fixed in position by a hold down nut that is threaded to the drive block inside the wash basket area or it may be fixed in position by one or more threaded fasteners. Therefore, if the wash basket is not aligned properly on the drive block, it will not be concentric about the central axis. Also, if the drive block is not aligned properly about the central axis, then the wash basket may not be concentric. So, it is important to have the overall alignment system of both the drive block and wash basket to provide a concentric spinning of the wash basket.
Traditional drive blocks are generally conical in shape and contact the generally conical outside surface of the wash basket bottom. Thus, the drive block and the wash basket abut circumferentially along a generally planar, conical surface. It is appreciated that there is basically one position in which the drive block and wash basket surfaces actually abut, but there are multiple possible positions for the drive block and wash basket to abut. Therefore, both the drive block and wash basket must be concentric about the central axis to obtain an accurate position.
Typically, the manufacturing process of an automatic washer includes the steps of configuring the drive block, spin drive tube, wash basket and hold down nut as close to concentric as possible. Acceptable tolerances for alignment about a central axis are determined for each step of the process; therefore, the tolerances stack up with each step. There would be better alignment about the central axis if the system of aligning the drive block and wash basket was done relative to each other to ensure overall concentricity of the spinning wash basket.
The present invention is directed to a system of aligning the wash basket of a washing machine concentrically about a central axis to decrease basket run out. The wash basket alignment system has a wash basket with a bottom wall having an outer surface and an inner surface, and a spin drive tube extending longitudinally along a generally central axis and through a central aperture in the basket bottom wall. Further, a rim defines the bottom wall central aperture and a wash basket center portion extends outward from the rim. The center portion is generally spherical in shape along the bottom wall inner surface. The wash basket has a mating portion extending outward from the center portion that is generally conical in shape along the bottom wall outer surface. There is a drive block having an upper portion with a central aperture for receiving the spin drive tube, a middle portion having a generally spherical shaped outside surface, and a threaded portion positioned between the upper portion and the middle portion.
It is an object of the invention to provide a wash basket alignment system wherein the drive block middle portion outside surface and the wash basket mating portion outer surface abut at a mating juncture when the drive block upper portion and threaded portion are inserted through the wash basket central aperture. The mating juncture is generally the circumference of a circle or ellipse.
Further, it is an object of the invention to provide a hold down nut having threads and a generally conical shaped underside surface with the threads mating with the drive block threaded portion. Additionally, the hold down nut underside surface and the wash basket center portion inner surface abut at a second juncture when the hold down nut threads are threadingly engaged with the drive block threaded portion. The second juncture is generally the circumference of a circle or ellipse.
It is an object of the invention to provide a hold down nut having threads and a generally conical underside surface with the hold down nut positioning the wash basket rim and central portion between the hold down nut and drive block middle portion when the hold down nut is threadingly engaged with the drive block threaded portion.
It is a further object of the invention to provide a hold down nut to position the mating portion outer surface with the drive block middle portion outside surface when the hold down nut is threadingly engaged with the drive block threaded portion. A circumferentially shaped mating juncture is formed that moves from a first position when the wash basket is not concentrically aligned about the central axis to a second position when the wash basket is concentrically aligned about the central axis.
Further, it is an object of the invention to provide a second juncture at which the wash basket center portion abuts the hold down nut conical shaped underside surface when the hold down nut threads threadingly engage the drive block threaded portion.
It is a further object of the invention to provide a mating juncture that may be shifted from a first position where the wash basket is not concentric about the central axis to a second position where the wash basket is generally concentric about the central axis, then the hold down nut can be threaded to the drive block threaded portion to maintain the second position. Further, the second juncture is shifted from a first position to a second position when the mating juncture is shifted from its first position to its second position and the second juncture second position is maintained by tightening the hold down nut to the drive block threaded portion.
It is a further object of the invention to provide a method of concentrically aligning a wash basket in an automatic washer having a spin drive tube extending longitudinally through a central aperture in the wash basket and a central aperture in a hold down nut and a central aperture in a drive block by positioning the wash basket aperture along a longitudinal axis, positioning the drive block aperture along the longitudinal axis, inserting a generally cylindrical portion of the drive block into the aperture of the wash basket thus having a portion of the drive block positioned within an interior area of the wash basket, resting an outer bottom surface of the wash basket on an outside surface of the drive block, threadingly engaging the hold down nut with mating threads on the drive block positioned in the interior area of the wash basket, spinning the wash basket along the longitudinal axis to determine concentricity of the wash basket, measuring concentricity of the wash basket along the longitudinal axis, aligning the wash basket along the longitudinal axis in response to the concentricity measurement, and tightening the threaded engagement of the lock nut to maintain the position of the wash basket.
It is also an object of the invention to provide a wash basket alignment system for an automatic washing machine having a wash basket with a bottom wall having an outer surface and an inner surface; a drive block with a middle portion having a generally spherical outside surface; and a generally central axis extending though a central aperture in the bottom wall and in the drive block. The drive block has a radius measured from a point on the central axis. The wash basket rim defines the wash basket central aperture, the wash basket center portion extends outward from the rim and is generally either spherical shaped or conical shaped. If the center portion is spherical shaped, it has a radius that intersects the central axis at a point.
It is an object of the invention to have the drive block point and the center portion point intersect the central axis at a common point when the center portion is spherical shaped.
Further, it is an object of the invention to provide a wash basket alignment system having a wash basket mating portion extending outward from the center portion that is either conical in shape or spherical in shape along the bottom wall outer surface. If the center portion is conical, a mating juncture is formed by the drive block middle portion and the mating portion such that a normal of the mating portion taken at the mating juncture passes through the drive block point. If the center portion is spherical, a mating juncture is formed by the mating portion and the drive bock middle portion such that the mating juncture is generally at a distance from the drive block point equal to the drive block radius.
It is also an object of the invention to provide a hold down nut having either a generally conical or convex underside surface, and a juncture formed by the center portion inner surface and the hold down nut underside surface. If the underside is conical then a normal of the hold down nut underside surface taken at the juncture passes through the drive block point.